Just about any insert/doubler you want to try here All are stain-free with minimal to normal wear.

Mother-Ease Lot: $10ppd
3x MotherEase Stay-Dry Doublers

Bamboo-Lover's Lot: $15ppd
2x Bububebe Bamboo Inserts
Weehuggers Bamboo Doubler
And one bamboo velour-topped two-tongue soaker with snaps. I believe it is from Softbums? We used it as a snap-in doubler for Motherease OS and Crickett's.